Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 38)

Aseembly and Installation
Chapter 2
2Ć25
Place PID modules in one or more chassis containing only PID
modules.
Supply +5V dc to each PIC module using one or more optional external
power supplies.
Place an on/off switch in the +5V dc lead to each PID module. This
allows you to remove power and replace a PID module without turning
off power to other PID modules in the chassis.
Removal of a Faulted PID Module
You can replace a faulted PID module in an I/O chassis using the
following procedure if each PID module is supplied with +5V dc from a
separate power supply or from a common supply with a switch in each
+5V dc lead.
1. Select the soft fault mode that allows PID modules to continue
operation when they lose communication with the PC processor. Do
this by means of your ladder program.
2. Turn off power to the I/O chassis. Block transfers cease but PID
modules continue to operate.
3. Turn off the +5V and +15V dc power to the faulted module.
4. Replace the faulted PID module.
5. Turn on power to the module and I/O chassis.
6. Restore the original soft fault mode to the PID modules.
If there are other modules and/or other PID modules without an external
+5V dc supply, they cease to operate when you turn off power to the
chassis. After restoring power, you must download PID control
parameters to PID modules through a load/enter sequence.
PID modules (rev C or later) have the option for you to select how outputs
respond when +5V dc is removed from the module. You select either
maximum or minimum, output using programming plus (refer to titled
Programming Plug Selection).
The backplane connector should be keyed to accept only this module after
its position in the I/O chassis has been determined.
Keying